| # | |
| # Random/OSRNG/posix.py : OS entropy source for POSIX systems | |
| # | |
| # Written in 2008 by Dwayne C. Litzenberger <dlitz@dlitz.net> | |
| # | |
| # =================================================================== | |
| # The contents of this file are dedicated to the public domain. To | |
| # the extent that dedication to the public domain is not available, | |
| # everyone is granted a worldwide, perpetual, royalty-free, | |
| # non-exclusive license to exercise all rights associated with the | |
| # contents of this file for any purpose whatsoever. | |
| # No rights are reserved. | |
| # | |
| # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, | |
| # EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF | |
| # MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND | |
| # NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS | |
| # BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN | |
| # ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN | |
| # CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE | |
| # SOFTWARE. | |
| # =================================================================== | |
| __revision__ = "$Id$" | |
| __all__ = ['DevURandomRNG'] | |
| import errno | |
| import os | |
| import stat | |
| from .rng_base import BaseRNG | |
| from Crypto.Util.py3compat import b | |
| class DevURandomRNG(BaseRNG): | |
| def __init__(self, devname=None): | |
| if devname is None: | |
| self.name = "/dev/urandom" | |
| else: | |
| self.name = devname | |
| # Test that /dev/urandom is a character special device | |
| f = open(self.name, "rb", 0) | |
| fmode = os.fstat(f.fileno())[stat.ST_MODE] | |
| if not stat.S_ISCHR(fmode): | |
| f.close() | |
| raise TypeError("%r is not a character special device" % (self.name,)) | |
| self.__file = f | |
| BaseRNG.__init__(self) | |
| def _close(self): | |
| self.__file.close() | |
| def _read(self, N): | |
| # Starting with Python 3 open with buffering=0 returns a FileIO object. | |
| # FileIO.read behaves like read(2) and not like fread(3) and thus we | |
| # have to handle the case that read returns less data as requested here | |
| # more carefully. | |
| data = b("") | |
| while len(data) < N: | |
| try: | |
| d = self.__file.read(N - len(data)) | |
| except IOError as e: | |
| # read(2) has been interrupted by a signal; redo the read | |
| if e.errno == errno.EINTR: | |
| continue | |
| raise | |
| if d is None: | |
| # __file is in non-blocking mode and no data is available | |
| return data | |
| if len(d) == 0: | |
| # __file is in blocking mode and arrived at EOF | |
| return data | |
| data += d | |
| return data | |
| def new(*args, **kwargs): | |
| return DevURandomRNG(*args, **kwargs) | |
| # vim:set ts=4 sw=4 sts=4 expandtab: | |